Electric-resistance material.



UNITED TES PATENT OFFICE.

MATTHEW A. HUNTER, OF TROY, NEW YORII.

ELECTRIC-RESISTANCE MATERIAL.

No Drawing.

To all whom it may concern:

Be it known that I, MATTHEW A. HUNTER, a subject of the King of Great Britain, residing in the city of Troy, county of Rensselaer, and State of New ork, have invented certain new and useful Improvements .in. Electric-Resistance Materials; and I do hereby declare the following to be a full,

clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. v

This invention relates to electric resistance materials and involves the production of a new alloy for use in the manufacture of electric resistance, elements of various kinds.

In accordance with the invention, an alloy is produced which may be used at relatively low cost in the production of electric resistance elements possessing to a marked degree the two primary requlsites of such resistances, namely, high electrical resistivity and low temperature coefficient of resistance. The new alloy is also specially adapted for use in resistance elements for the reasons that it has a high melting point, will not corrode when worked ,hot and has a low thermo-electromotive force against copper.

The new alloy made-in accordance with the invention consists of nickel, copper and chromium, the proportion of nickel being large relatively to the proportion of copper and chromium.

Alloys of nickel and chromium have been used heretofore as a resistancematerial and the resultsthus obtained are very good. I have discovered, however, that by properly alloying nickel, copper and chromium, a resistance material may be produced which is much more efiicient anddesirable. I have found that though the addition of chromium to copper has but little effect upon theelectric resistance thereof, the addition of chromium to an alloy of copper and nickel in -meter cube at 20 C. and to have at that temperature coefiicient of resistance of the alloy. Otherwise stated, I have found that the addition of,a small proportion of copper to an alloy of chromium and nickel results in materially increasing the resistivity of the alloy. It is important, however, that the proportion of copper should be small Specification of Letters Patent. 7 PatentedJan, 11, 1916, Application filed May 21, 1915. erial No. 29,589. i

In the alloy'which I have found to be most suitable for general use asia resistance ma-.

t'erial, the nickel and copper are in the proportion of 75 to 95 arts of nickel to 25 to .5 parts of copper. oodresults may be obtained outside this range of variation, espewhen but little chromium is used, but

daily I find this relation of the nickel and copper elements to be best. As the proportion of nickel is increased beyond 95 parts of nickel to 5 parts of copper and as it is decreased below 75 pa'rts of nickel to-25 parts of 0019- per, a marked decrease occurs in the resistivity of the alloy. The amount of chr0- mium added .to the mixture-is small com; ared to the nickel; preferably it is from fteen to twenty-five parts by weight of chromium to one hundred parts of nickel and copper. The higher proportions of chromium have a beneficial reflect in increasing the resistivity, but then practical difliculties in the mechanicaltreatment, of the material become more pronounced. An amount of chromium less than that above named as being best would increase the resistance of a given coppernickel mixture and is especially desirable when the proportion .of copper is made larger than that above indicated for any reason, but the resistance of the material thus produced would be less than that obtained by employing the larger amount of chromium in combination wlth nickel and copper-in the proportions above indicated.

I have had particularly good results with an alloy .'consisting of parts of nickel to 15 parts of copper, with 20 parts of chromium to 100 parts of nickel and copper. Such an alloy has'ibeen found to have a resistivity of about 113 microhms per centitemperature a temperature coeflicient of resistance of about 0.000078 ohms per degree centigrade per ohm. Y What I claim is: g

1.'An electric resistance material consisting of an alloy of nickel, copper and chromium, the nickel and copper being in the relation of 75 parts to 95 parts of nickel to 25' parts to 5 parts of copper substantially as described.

2. An electric resistance material consisting of a large proportion of nickel, a small proportion of copper, and chromium amounting to from 10 parts to 25 parts to 100 parts of the nickel and copper; substantially as described 3. An electric resistance material consisting of an alloy of nickel, copper and chromium, the copper and nickel being in. the proportion of from 5 to 25 parts of copper to 95 to 75 parts of nickel and the chromium being in the proportion of from 10 to 25 parts of chromium to 100 parts of nickel and copper; substantially as described.

4. An electric resistance material consistmeame 

